Geopolymer concrete for curing at normal temperature

Abstract

Recent studies have shown that the properties of emerging low-emission geopolymer binders are similar or superior to those of the OPC binder traditionally used for concrete. Most of the previous studies in literature used heat curing to demonstrate the properties of geopolymer mixtures. Though heat curing is a common practice for making precast concrete products, it is an energy consuming process and can be viewed as a limitation for cast-in-situ applications of concrete. This paper presents an investigation on the behaviour of geopolymer concrete cured at relatively low temperature without any additional heat for the curing process. Small proportions of ground granulated blast furnace slag (GGBFS) were added with fly ash in order to improve the early age properties of geopolymer concrete. Test samples were cured at a temperature of 20-23oC. Results show that inclusion of slag helped achieve setting time and compressive strength comparable to those of OPC concrete at the early ages. Fracture properties were similar to those of conventional OPC concrete. Drying shrinkage of geopolymer concrete reduced when slag was included in the binder. Permeability properties and sulphate resistance of slag blended fly ash geopolymer are found to be better than those of OPC concrete.